help (rear subframe bushes or something else..)

[7.77]

so:

my rear bushes (powerflex for the subframe and RTAB, and bmw's for the others) have been replaced for the ring/spa trip in May.

since, i have a bad feeling of the balance of the car: my car is shaking/rolling from right to left. something like a play somewhere at the back. When i drive hard on corner, after big roll, when the car is on the suspension, it is okay. but when i change corner, there is a big movment of the car till the car is on the suspension, and after it is ok. I run PSS10 (1.5 years old), position 10 (harder). I have checked the suspension and it is ok.

i think the play comes from the rear subframe
i decided to have the subframe powerflex replaced by oem.

same problem.

please see the pictures (rear/top subframe bushe) and tell me if they are fitted in the right way:

powerflex



look at the gap at the top ??

oem (i can see the rear subframe moving when i lift the car):






if i compare with this subframe (taking on the web), they seems to be fitted on the wrong way)



please help me

[AlexGTT]

Hope it's not this 7.77 but have you had the back floor subframe mount points checked for the dreaded cracks. Contact Simpson Motorsport or a specialist you trust. They will tell you exactly where to look to identify the cracking points.

Hope it's not this but they will all do it sooner or later, depending on how hard the car is used.

[NZ_M3]

They are fitted the right way around - the photo of the subframe on the floor is upside down.

So let me try and get what you are saying - are you saying that through corner changes and you load the suspension up (say the left side) and then as you transition into the next corner (now the right side) the rear end feels lose? Are there any unusual noise as you go through this transition?

Sounds almost to me like that suspension is running out of rebound (typical of PSS10 - they have a very short range rebound compared to the progressive damping valving).

For rear subframe mount - Check the boot and see if any of the seals have cracked, then jack up the car and check the front left mount point and the rear right (those are the first ones to crack) - best to drop the subframe to check, as initial cracks form under the bushes.

Check your swaybar mount too, something might be lose or worn there.

[7.77]

So let me try and get what you are saying - are you saying that through corner changes and you load the suspension up (say the left side) and then as you transition into the next corner (now the right side) the rear end feels lose? Are there any unusual noise as you go through this transition?

exactly, but no noise. the problem is between 2 loads of suspension, even on straight roads, the car is shaking

Sounds almost to me like that suspension is running out of rebound (typical of PSS10 - they have a very short range rebound compared to the progressive damping valving).

For rear subframe mount - Check the boot and see if any of the seals have cracked, then jack up the car and check the front left mount point and the rear right (those are the first ones to crack) - best to drop the subframe to check, as initial cracks form under the bushes.

i havn't seen any cracks

Check your swaybar mount too, something might be lose or worn there

will change the swaybar links and rubber. something strange: nothing before changing the bushes !!

[AlexGTT]

7.77, the floor cracks are very hard to see. You have to look in very specific places, which is why I recommend you speak to someone who can at least send you precise pictures of where the cracks can be seen with the subframe on. Of course, to really check you have to remove the subframe.

I'll try and link the thread which has some good info and pictures of a car having this fixed.

[7.77]

everything was ok before changing the bushes.

i had the same problem when i first drive the car with the pss10, it was on the smoothest position (1). I just turned on position10 and it was okay. Do you think the dampers could be worn ? even with no leak and good when moving them with my hand ?

look at the roll of the car